How Is Nanotechnology Used in Sunscreen?

I recently heard that some sunscreens use nanotechnology. What is it?

Nanotechnology, simply put, is the science of engineering particles to very, very small sizes. In sunscreen, smaller particles of zinc oxide (or other sun-blocking substances) create a shield that's strong but sheer (not white or filmy) on skin. Nanotech is big in the beauty industry because it improves absorption of active ingredients (so wrinkle creams can better smooth fine lines, for example). Consumer advocates worry that not enough is known about whether tinier, more deeply penetrating ingredients build up in the body and, if so, whether that's bad. The FDA hasn't seen evidence of danger, but it convened an investigative task force in 2008; guidelines are pending.